Device for detecting faults in rotary electric circuits of brushless exciters of synchronous machines

ABSTRACT

The proposed device includes an induction pickup for checking the circuits under control mounted close to these rotary circuits conducting an electric current. The output of the induction pickup of the controllable circuits is connected to one of the inputs of a signal distributing unit made in the form of a trigger counter whose outputs are connected to a diode matrix. Connected to the other input of the signal distributing unit is the output of an interrogation pulse shaping unit. The output of the signal distributing unit is connected to the inputs of a unit for controlling and indicating the condition of the circuits under control employed for light signalling about a fault and for sending signals to the system for automatic control and protection of the exciter and the synchronous machine excited thereby.

0 muted States Patent [191 [111 3,733,518 Polulyakh et al. 51 May 15,1973 [54] DEVICE FOR DETECTING FAULTS IN [56] References Cited ROTARYELECTRIC CIRCUITS OF UNITED STATES PATENTS BRUSHLESS EXCITERS OF S CRONOUS MAC NES 3,435,327 3/1969 Merhof et al ..322/99 PrimaryExaminer-James D Trammell [76] Inventors: Valentin StepanovrchPolulyakh, Atmmey Eric waters et ulitsa II Pyatiletki, 19, kv. 118;Viktor Nilolaevich Khodkevich, ulitsa [57] ABSTRACT E T P F Krala 8; Vlktor The proposed device includes an induction pickup for ljlgonev'ch juhrsa checking the circuits under control mounted close to 35;Semenovlch these rotary circuits conducting an electric current.Klldlshev, Plekhanovskaya 41, The output of the induction pickup of thecontrollable 55, all of Kharkov, circuits is connected to one of theinputs of a signal [22] Filed: Man 3 1972 distributing unit made in theform of a trigger counter whose outputs are connected to a diode matrix.Con- PP'- N08 231,671 nected to the other input of the signaldistributing unit is the output of an interrogation pulse shaping unit.The output of the signal distributing unit is connected [52] U.S. Cl..317/13 R, 318/180, 322/99 to the inputs of a unit for controlling andindicating 51 Int. Cl. ..H02h 7/06 the condition of the circuits undercontrol p y [58] Field of Search ..317 13 R; 324/34, light Signallingabout a fault and Sending Signals to the system for automatic controland protection of the exciter and the synchronous machine excitedthereby.

3 Claims, 5 Drawing Figures PATENTEB MAY 1 51973 SHEET 2 BF 3 PATENTEG W1 9 3 SHEET 3 [IF 3 1 DEVICE FOR DETECTING FAULTS IN ROTARY ELECTRICCIRCUITS OF BRUSI-ILESS EXCITERS OF SYNCHRONOUS MACHINES The presentinvention relates to devices for detecting faults in rotary electriccircuits of brushless exciters of synchronous machines.

Known in the art is a device for detecting faults (fuse blowing) inrotary electric circuits of a brushless exciter of a synchronous machinewith the aid of n stationary coils mounted on U-shaped cores installednear the rotary circuits of the rectifier of the brushless exciter and mstationary switching coils mounted on U- shaped stationary coresarranged near the rotary magnetic element disposed on the periphery ofthe rotor.

This device is disadvantageousin a large quantity of n and m stationarycoils necessary in systems employing multiphase or three-phase brushlessexciters, each phase having a plurality of branches, or in systems builtaround bridge-circuit rectifiers a fuse being provided in each branch ofthis rectifier.

An increase in the amount of coils mounted directly on the brushlessexciter close to its rotating components and poor access to the abovecoils during the operation of the exciter increase the probability oftheir failure. Besides, this fact results in an increase in the quantityof wires connecting the coils with the logical unit of the device, thusincreasing the quantity of elements in the logical unit of the device.This reduces the reliability of the device and complicates itsoperation.

An object of the present invention is to provide a device for detectingfaults in rotary electric circuits of a brushless exciter of asynchronous machine which by means of a non-contact method wouldcontinuously control the condition of the rotary circuits of a brushlessexciter with indication of the ordinal number of a faulty circuit.

Another object of the invention is to send a signal varying as afunction of the number of the faulty circuits to a system forautomatically controlling and protecting the brushless exciter and thesynchronous machine excited thereby.

Still another object of the invention is to eliminate the abovementioned disadvantages.

These and other objects are accomplished in a device for detectingfaults in rotary electric circuits of brushless exciter of a synchronousmachine comprising an induction pickup for checking the condition of thecircuits under control mounted on the stationary part of the brushlessexciter close to the circuits being controlled which, according to theinvention, is provided with a distribution unit one input of whichreceives the signals from the induction pickup checking the condition ofthe circuits under control, while two other inputs receive signals froma unit for shaping interrogation pulses and a unit for shaping startinginterrogation pulses, whereas the outputs of the distribution unit areconnected to a unit for controlling and indicating the condition of thecircuits under control.

It is advisable that in the device for detecting faults in rotaryelectric circuits of brushless exciters of synchronous machines the unitfor shaping interrogation pulses is built around a steel toothed rotormounted on the shaft of the brushless exciter and having a number ofteeth equal to m 1 of the circuits under control; a permanent magnetwith coils on its poles is preferably mounted near this rotor, theterminals of the coils being connected to the input of ashaper-amplifier.

Besides, it is advisable that in the device for detecting faults inrotary electric circuits of brushless exciters the unit for shapingstarting interrogation pulses is built around a single-tooth steel rotormounted on the shaft of the brushless exciter; a permanent magnet withcoils on its poles is preferably mounted close to this unit, theterminals of the coils being connected to the input of ashaper-amplifier.

The proposed device provides for continuous control of the integrity ofthe fuses of a brushless exciter and this fact enhances the reliabilityof operation of a synchronous machine equipped with such an exciter.

The possibility of exact indication of a fault in any circuit of thebrushless exciter during the operation of the synchronous machinereduces the time necessary for eliminating the fault at a short-termstoppage of the synchronous machine.

The continuous control of the condition of the rotary electric circuitsand fast response of the device make it possible to separate a signalacting on the system for automatic control of the brushless exciter,thus quickly changing the operating conditions of the exciter andsynchronous machine excited thereby according to a predetermined law andthis fact impedes the development of the fault in the brushless exciterand increases the trouble-free operation of the synchronous machine.

The invention will be better understood from the following detaileddescription of some embodiments thereof, reference being made to theaccompanying drawings, in which:

FIG. 1 is a block diagram of the device for detecting faults in rotaryelectric circuits of brushless exciters of synchronous machines;

FIG. 2 represents the device for detecting faulty fuses in aneighteen-phase or three-phase brushless exciter, each phase of which hassix parallel branches whose rectifier is built around a half-waverectifying circuit;

FIG. 3 shows the device for detecting faulty fuses in eighteen-phase orthree-phase brushless exciter, each phase of which has six parallelbranches whose rectifier is built around a bridge rectifying circuit;

FIG. 4 is a diagram of the half-wave semiconductor rectifier;

FIG. 5 is a diagram of the bridge semiconductor rectifier.

The fault of electric circuits is supposed to be a blowing of fuses,which are inserted in series with semiconductor rectifiers, due to shortcircuits of the semiconductor rectifiers or their overloading (when therectifier current exceeds its specified value).

The device for detecting faults in rotary electric circuits of brushlessexciters of synchronous machines comprises an induction pickup l forchecking the condition of the circuits under control (FIG. 1) installedclose to the rotary electric circuits through which an electric currentflows. The output of the induction pickup checking the condition of thecircuits under control is connected to one of the inputs of the signaldistributing unit 2. The other input of the signal distributing unit 2is connected to the output of an interrogation pulse shaping unit 3.Starting interrogation pulses from a starting interrogation pulseshaping unit 4 are fed to the third input of the signal distributingunit 2. The outputs of the signal distributing unit 2 are connected tothe inputs of a unit 5 for controlling and indicating the condition ofthe circuits under control which is intended for light signalling aboutthe faults and for sending signals to a system for automatic control andprotection of the exciter and the synchronous machine excited thereby.

In the absence of faults in the controllable rotary electric circuits ofthe brushless exciter a voltage pulse is generated in the inductionpickup 1 checking the condition of the circuits under control, whichpulse is induced in each circuit passing under the poles of thepickup 1. In this case at the output of the induction pickup l checkingthe condition of the circuits under control there appear voltage pulsesthe number of which is equal to the number of circuits being controlled.The pulses from the output of the induction pickup l checking thecondition of the circuits under control are fed to the input of thesignal distributing unit 2.

In the initial position all the outputs of the unit 2, except for thesecond output, are bridged. Owing to this fact, the first pulse from theoutput of the induction pickup 1 checking the condition of the circuitsunder control appears only at the first input of the signal distributing unit 2. After passing the first pulse from the output of theinduction pickup 1 checking the condition of the circuits under control,a pulse from the interrogation pulse unit 3 is applied to the otherinput of the signal distributing unit 2 which sets this unit in such aposition that all its outputs, except for the second, are bridged. Thesecond pulse from the output of the induction pickup 1 checking thecondition of the circuits under control following the first pulse fromthe interrogation pulse unit 3 will appear only at the second output ofthe signal distributing unit 2, etc. After the armature of the brushlessexciter has made a complete revolution, a pulse from the startinginterrogation pulse shaping unit 4 is applied to the third input of thesignal distributing unit 2 and the latter is set to its initialposition, while the process of distribution of the signals from theoutput of the induction pickup 1 checking the condition of the circuitsunder control is resumed. From the outputs of the signal distributingunit 2 the voltage pulses are fed to the inputs of the unit 5 forcontrolling and indicating the condition of the circuits under control.In the case of failure of one or several rotary electric circuits of thebrushless exciter these are deenergized. When the faulty rotary electriccircuits pass about the poles of the induction pickup 1 checking thecondition of the circuits under control, no voltage pulses appear at itsoutput.

In this connection, there will be no signals at the respective outputsof the signal distributing unit 2 and at the inputs of the control andindication unit 5 which are associated with these outputs of the signaldistributing unit 2.

The illuminated indicator boards of the control and indication unit 5will indicate the quantity and numbers of the faulty circuits. A signalis produced at the output of the control and indication unit 5 whichdepends on the amount of the faulty circuits and can be used in thesystem for automatic control of excitation and protection of the machineagainst overloads.

Given below is a description of the device according to theabove-mentioned block diagram with reference to the accompanyingdrawings which disclose the arrangement of the units 1, 2, 3, 4 and 5and the electric connection therebetween.

The induction pickup 1 for checking the condition of the circuits undercontrol (FIG. 2) consists of a U- shaped ferromagnetic core with coilsat its poles which is mounted on the stationary part of the brushlessexciter near its rotary electric circuits 6 so as to obtain the maximumcurrent in the circuits 6 when these circuits move under the pickup 1.At the moment when the electric circuits 6 conducting an electriccurrent pass under the induction pickup l checking the condition of thecircuits under control, voltage pulses are induced in its coils whichare amplified by the amplifier-shaper 7 and are fed to the power supplybar of the diode matrix 8 of the signal distributing unit 2. The signaldistributing unit 2 consists of a binary trigger/counter in which theamount of triggers 9 depends on the amount of the circuits 6 undercontrol (in the given case five triggers 9) and a diode matrix 8 and isintended for separation of the amplified voltage pulses which'appear inthe induction pickup 1 checking the condition of the circuits undercontrol and for distribution of these pulses through its individualoutputs. The signal number of outputs of the distributing unit 2 isequal to the number of the circuits 6 under control (in this caseeighteen outputs).

The output bars of the diode matrix 8 serve as outputs of the signaldistributing unit 2. The complementing input of the binary counter ofthe signal distributing unit 2 is connected to the output of theinterrogation pulse shaping unit 3 which consists of a steel toothedrotor 10 mounted on the shaft of the brushless exciter, the amount ofteeth 11 being equal to m-l (where m is the number of phases of themultiphase brushless exciter or the number of parallel branches of thethreephase brushless exciter), a permanent U-shaped magnet 12 with awinding 13 which is mounted near the rotor 10 on the stationary part ofthe exciter, and an amplifier-shaper 14 whose input is connected to theoutputs of the winding 13.

The signals from the output of the starting interrogation pulse shapingunit 4, which differs from the interrogation pulse shaping unit 3 inthat its rotor 15 has only one tooth 16 facing the tooth replacing spaceon the rotor 10, are fed to the bar for resetting the binary triggercounter of the signal distributing unit 2.

The outputs of the signal distributing unit 2 are connected to theinputs of the control and indication unit 5 which is built around ofamplifiers (not shown), the quantity of which is determined by thenumber of the circuits 6 under control (in this specified caseeighteen), each being loaded with an intermediate relay whose contactsare used in the light-signalling circuits and in the system for controland protection of the brushless exciter of the synchronous machine Inthe absence of faults in the rotary electric circuits 6 of the brushlessexciter (the fuses shown in FIG. 4 are not blown up), each circuit 6passing under the induction pickup 1 (FIG. 2) induces a voltage pulse inthe coils of the pickup l for checking the condition of the circuitsunder control.

Thus, during one revolution of the armature of the brushless excitervoltage pulses are induced across the terminals of the coil of theinduction pickup 1 checking the condition of the circuits under control,the quantity of these pulses being equal to that of the circuits 6 undercontrol (in this case eighteen). The voltage pulses are amplified by theamplifier-shaper 7 and are applied to the power supply bar of the diodematrix 8 of the signal distributing unit 2.

In the original position all the outputs of the signal distributingunit, except for the first, are bridged. Owing to this fact, the firstpulse of the induction pickup l checking the condition of the circuitsunder control will appear only at the first output of the signaldistributing unit 2. After the passage of the first pulse from theinduction pickup l checking the condition of the circuits under control,an interrogation pulse appears at the output of the interrogation pulseshaping unit 3 and this pulse is applied to the complementing input ofthe binary trigger counter of the signal distributing unit 2. In thiscase the trigger counter and, therefore, the diode matrix 8 are switchedso that all the outputs of the signal distributing unit 2, except forits sec-' ond output, are bridged and the second pulse from theinduction pickup l checking the condition of the circuits under controlwill appear only at the second output of the signal distributing unit 2.The second pulse from the interrogation pulse shaping unit 3 willcommutate the signal distributing unit 2 so that the third pulse fromthe induction pickup 1 checking the condition of the circuits undercontrol will appear at the third output only, etc. During one revolutionof the armature of the brushless exciter at each output of the signaldistributing unit 2 there appears a voltage pulse corresponding to theintegrity of the circuits 6 under control.

After the armature of the brushless exciter has completed onerevolution, a pulse appears at the output of the starting interrogationpulse shaping unit 4 which is fed to the bar for resetting the binarycounter of the signal distributing unit 2. The signal distributing unit2 returns to its original position when all its outputs, except for thefirst, are bridged, and the process of distribution of the signals fromthe induction pickup l checking the condition of the circuits undercontrol is resumed. The device for detecting faults in rotary electriccircuits is shown in FIG. 2 at the moment when a pulse appears at theoutput of the starting interrogation pulse shaping unit 4.

From the outputs of the signal distributing unit 2 the voltage pulsesare fed to the inputs of the control and indication unit 5 to energizethe intermediate relays. In the case of fault of one or severalsemiconductor rectifiers 18 of the rectifier unit of the brushlessexciter (FIG. 4) they are disconnected by means of fuses 17 and nocurrent flows through the circuits 6 being controlled.

When the deenergized circuits 6 (FIG. 2) to be controlled pass under theinduction pickup l checking the condition of the circuits under control,no voltage pulses are induced in the winding of the pickup 1.Consequently, there will be no signals at the corresponding outputs ofthe signal distributing unit 2 and this fact will result in deenergizingthe intermediate relays (not shown) inserted at the outputs of theamplifiers whose inputs are connected to the outputs of the signaldistributing unit 2 which in this case sends no signal. The relays, whendeenergized, through their contacts close the circuits of the signallamps which indicate the quantity and numbers of the blown-up fuses.

Depending on the method of introducing a signal into the system ofautomatic control and protection of the machine, there can be employedboth normally open and normally closed contacts of the relays.

The outputs of the control and indication unit 5 are composed by theterminals of the contacts of the relays or by the terminals of somecombinations of the contacts necessary for acting upon the automaticregulator of excitation and upon the system for protection of thebrushless exciter.

If the brushless exciter is built around a bridge-circuit rectifier(FIG. 5), the number of fuses is doubled. To control the condition ofthe additional fuses 17, the system must be modified as follows.

An induction pickup 19, similar to the induction pickup 1, is added tothe system for checking the condition of the circuits under control(FIG. 3), the former being shifted in the direction of rotation of thebrushless exciter (or opposite to this direction) relative to the pickup1 for a pole division of the exciter to reverse the polarity of theelectric current flowing through the circuits 6 passing under theinduction pickup 19 checking the condition of the circuit under control.The terminals of the coil of the induction pickup 19 checking thecondition of the circuits under control are connected to the input of anamplifier-shaper 20.

Added into the interrogation pulse shaping unit 3 and into the startinginterrogation pulse shaping unit 4 are U-shaped permanent magnets 21with windings 22 and amplifier-shapers 23 (one permanent magnet and oneamplifier shaper for each of said units). The U-shaped permanent magnets21 with windings 22 must also be shifted relative to the previouslyinstalled permanent magnets 12 with windings 13 for a value equal to onepole division of the brushless exciter. Besides the above modifications,the device is provided with a signal distributing unit 24 similar to thesignal distributing unit 2 and with a control and indication unit 25similar to the control and indication unit 5.

The modified device operates in a similar way as the device shown inFIG. 2 but is distinguished from the latter, which checks the conditionof the circuit 6 under control for one half wave only, in that thedevice shown in FIG. 3 is suitable for checking the condition of thecircuits 6 under control during the positive and negative half waves.

We claim 1. A device for detecting faults in rotary electric circuits ofbrushless exciters of synchronous machines comprising in combination: asignal distributing unit made in the form of a trigger counter whoseoutputs are connected to a diode matrix; an induction pickup forchecking the condition of the circuits under control mounted on thestationary part of the brushless exciter near the rotary circuits undercontrol; an amplifiershaper of said induction pickup whose output isconnected to the bar for power supply of said diode matrix while theterminals of the winding of the induction pickup checking the conditionof the circuits under control are connected to the input of saidamplifiershaper; an interrogation pulse shaping unit whose output isconnected to the complementing input of said trigger counter of thesignal distributing unit; a starting interrogation pulse shaping unitwhose output is connected to the bar for resetting said trigger counterof the signal distributing unit; a control and indication unit whoseinputs are connected to the output bars of said diode matrix of thesignal distributing unit; said control and indication unit consists ofamplifiers the number of which is equal to the number of the circuitsunder control, each amplifier being loaded with an ac- 7 8 tuatingelement sending a signal about faults in the ropoles, the terminals ofsaid coils being connected to the tary electric circuits to the systemfor automatic coninput of an amplifier-shaper. trol of the brushlessexciter of the synchronous ma- 3. A device for detecting faults inrotary electric circhine. cuits of brushless exciters of synchronousmachines as 2. A device for detecting faults in rotary electriccirclaimed in claim 1, in which the starting interrogation cuits ofbrushless exciters of synchronous machines as pulse shaping unitconsists of a steel rotor with a single claimed in claim 1, in which theinterrogation pulse tooth mounted on the shaft of the brushless exciter;a shaping unit consists of a steel toothed rotor mounted permanentmagnet with coils on its poles is mounted on the shaft of the brushlessexciter having a quantity near said unit, the terminals of said coilsbeing conof teeth equal to m-l circuits under control; mounted 10 nectedto the input of the amplifier-shaper. near said unit is a permanentmagnet with coils on its

1. A device for detecting faults in rotary electric circuits ofbrushless exciters of synchronous machines comprising in combination: asignal distributing unit made in the form of a trigger counter whoseoutputs are connected to a diode matrix; an induction pickup forchecking the condition of the circuits under control mounted on thestationary part of the brushless exciter near the rotary circuits undercontrol; an amplifier-shaper of said induction pickup whose output isconnected to the bar for power supply of said diode matrix while theterminals of the winding of the induction pickup checking the conditionof the circuits under control are connected to the input of saidamplifier-shaper; an interrogation pulse shaping unit whose output isconnected to the complementing input of said trigger counter of thesignal distributing unit; a starting interrogation pulse shaping unitwhose output is connected to the bar for resetting said trigger counterof the signal distributing unit; a control and indication unit whoseinputs are connected to the output bars of said diode matrix of thesignal distributing unit; said control and indication unit consists ofamplifiers the number of which is equal to the number of the circuitsunder control, each amplifier being loaded with an actuating elementsending a signal about faults in the rotary electric circuits to thesystem for automatic control of the brushless exciter of the synchronousmachine.
 2. A device for detecting faults in rotary electric circuits ofbrushless exciters of synchronous machines as claimed in claim 1, inwhich the interrogation pulse shaping unit consists of a steel toothedrotor mounted on the shaft of the brushless exciter having a quantity ofteeth equal to m-1 circuits under control; mounted near said unit is apermanent magnet with coils on its poles, the terminals of said coilsbeing connected to the input of an amplifier-shaper.
 3. A device fordetecting faults in rotary electric circuits of brushless exciters ofsynchronous machines as claimed in claim 1, in which the startinginterrogation pulse shaping unit consists of a steel rotor with a singletooth mounted on the shaft of the brushless exciter; a permanent magnetwith coils on its poles is mounted near said unit, the terminals of saidcoils being connected to the input of the amplifier-shaper.